题目内容
(12分)已知地球半径为R,地球表面重力加速度为g,不考虑地球自转的影响.
(1)推导第一宇宙速度v1的表达式;
(2)若卫星绕地球做匀速圆周运动,运行轨道距离地面高度为h,求卫星的运行周期T.
(1)推导第一宇宙速度v1的表达式;
(2)若卫星绕地球做匀速圆周运动,运行轨道距离地面高度为h,求卫星的运行周期T.
(1)
(2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241500327021045.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150032686429.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241500327021045.png)
试题分析:(1)设卫星的质量为m,地球的质量为M
在地球表面附近满足
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150032749873.png)
得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150032983688.png)
卫星做圆周运动的向心力等于它受到的万有引力
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150033045981.png)
①式代入②式,得到
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150033092545.png)
(2)考虑①式,卫星受到的万有引力为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241500332951432.png)
由牛顿第二定律
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241500333571074.png)
③④式联立解得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241500334661146.png)
点评:偏易。把天体运动当做匀速圆周运动,向心力来源于万有引力,其基本关系为:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150032749873.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824150033638960.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241500337001608.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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